diff --git a/tests/Unit/OutputFormatTest.php b/tests/Unit/OutputFormatTest.php
new file mode 100644
index 00000000..482be82f
--- /dev/null
+++ b/tests/Unit/OutputFormatTest.php
@@ -0,0 +1,307 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Sabberworm\CSS\Tests\Unit;
+
+use PHPUnit\Framework\TestCase;
+use Sabberworm\CSS\OutputFormat;
+
+/**
+ * @covers \Sabberworm\CSS\OutputFormat
+ */
+final class OutputFormatTest extends TestCase
+{
+    /**
+     * @var OutputFormat
+     */
+    private $subject;
+
+    protected function setUp(): void
+    {
+        $this->subject = new OutputFormat();
+    }
+
+    /**
+     * @test
+     */
+    public function getStringQuotingTypeInitiallyReturnsDoubleQuote(): void
+    {
+        self::assertSame('"', $this->subject->getStringQuotingType());
+    }
+
+    /**
+     * @test
+     */
+    public function setStringQuotingTypeSetsStringQuotingType(): void
+    {
+        $value = "'";
+        $this->subject->setStringQuotingType($value);
+
+        self::assertSame($value, $this->subject->getStringQuotingType());
+    }
+
+    /**
+     * @test
+     */
+    public function setStringQuotingTypeProvidesFluentInterface(): void
+    {
+        self::assertSame($this->subject, $this->subject->setStringQuotingType('"'));
+    }
+
+    /**
+     * @test
+     */
+    public function getRGBHashNotationInitiallyReturnsTrue(): void
+    {
+        self::assertTrue($this->subject->getRGBHashNotation());
+    }
+
+    /**
+     * @return array<string, array{0: bool}>
+     */
+    public static function provideBooleans(): array
+    {
+        return [
+            'true' => [true],
+            'false' => [false],
+        ];
+    }
+
+    /**
+     * @test
+     *
+     * @dataProvider provideBooleans
+     */
+    public function setRGBHashNotationSetsRGBHashNotation(bool $value): void
+    {
+        $this->subject->setRGBHashNotation($value);
+
+        self::assertSame($value, $this->subject->getRGBHashNotation());
+    }
+
+    /**
+     * @test
+     */
+    public function setRGBHashNotationProvidesFluentInterface(): void
+    {
+        self::assertSame($this->subject, $this->subject->setRGBHashNotation(true));
+    }
+
+    /**
+     * @test
+     */
+    public function getSemicolonAfterLastRuleInitiallyReturnsTrue(): void
+    {
+        self::assertTrue($this->subject->getSemicolonAfterLastRule());
+    }
+
+    /**
+     * @test
+     *
+     * @dataProvider provideBooleans
+     */
+    public function setSemicolonAfterLastRuleSetsSemicolonAfterLastRule(bool $value): void
+    {
+        $this->subject->setSemicolonAfterLastRule($value);
+
+        self::assertSame($value, $this->subject->getSemicolonAfterLastRule());
+    }
+
+    /**
+     * @test
+     */
+    public function setSemicolonAfterLastRuleProvidesFluentInterface(): void
+    {
+        self::assertSame($this->subject, $this->subject->setSemicolonAfterLastRule(true));
+    }
+
+    /**
+     * @test
+     */
+    public function getSpaceAfterRuleNameInitiallyReturnsSingleSpace(): void
+    {
+        self::assertSame(' ', $this->subject->getSpaceAfterRuleName());
+    }
+
+    /**
+     * @test
+     */
+    public function setSpaceAfterRuleNameSetsSpaceAfterRuleName(): void
+    {
+        $value = "\n";
+        $this->subject->setSpaceAfterRuleName($value);
+
+        self::assertSame($value, $this->subject->getSpaceAfterRuleName());
+    }
+
+    /**
+     * @test
+     */
+    public function setSpaceAfterRuleNameProvidesFluentInterface(): void
+    {
+        self::assertSame($this->subject, $this->subject->setSpaceAfterRuleName("\n"));
+    }
+
+    /**
+     * @test
+     */
+    public function getSpaceBeforeRulesInitiallyReturnsEmptyString(): void
+    {
+        self::assertSame('', $this->subject->getSpaceBeforeRules());
+    }
+
+    /**
+     * @test
+     */
+    public function setSpaceBeforeRulesSetsSpaceBeforeRules(): void
+    {
+        $value = ' ';
+        $this->subject->setSpaceBeforeRules($value);
+
+        self::assertSame($value, $this->subject->getSpaceBeforeRules());
+    }
+
+    /**
+     * @test
+     */
+    public function setSpaceBeforeRulesProvidesFluentInterface(): void
+    {
+        self::assertSame($this->subject, $this->subject->setSpaceBeforeRules(' '));
+    }
+
+    /**
+     * @test
+     */
+    public function getSpaceAfterRulesInitiallyReturnsEmptyString(): void
+    {
+        self::assertSame('', $this->subject->getSpaceAfterRules());
+    }
+
+    /**
+     * @test
+     */
+    public function setSpaceAfterRulesSetsSpaceAfterRules(): void
+    {
+        $value = ' ';
+        $this->subject->setSpaceAfterRules($value);
+
+        self::assertSame($value, $this->subject->getSpaceAfterRules());
+    }
+
+    /**
+     * @test
+     */
+    public function setSpaceAfterRulesProvidesFluentInterface(): void
+    {
+        self::assertSame($this->subject, $this->subject->setSpaceAfterRules(' '));
+    }
+
+    /**
+     * @test
+     */
+    public function getSpaceBetweenRulesInitiallyReturnsEmptyString(): void
+    {
+        self::assertSame('', $this->subject->getSpaceBetweenRules());
+    }
+
+    /**
+     * @test
+     */
+    public function setSpaceBetweenRulesSetsSpaceBetweenRules(): void
+    {
+        $value = ' ';
+        $this->subject->setSpaceBetweenRules($value);
+
+        self::assertSame($value, $this->subject->getSpaceBetweenRules());
+    }
+
+    /**
+     * @test
+     */
+    public function setSpaceBetweenRulesProvidesFluentInterface(): void
+    {
+        self::assertSame($this->subject, $this->subject->setSpaceBetweenRules(' '));
+    }
+
+    /**
+     * @test
+     */
+    public function getSpaceBeforeBlocksInitiallyReturnsEmptyString(): void
+    {
+        self::assertSame('', $this->subject->getSpaceBeforeBlocks());
+    }
+
+    /**
+     * @test
+     */
+    public function setSpaceBeforeBlocksSetsSpaceBeforeBlocks(): void
+    {
+        $value = ' ';
+        $this->subject->setSpaceBeforeBlocks($value);
+
+        self::assertSame($value, $this->subject->getSpaceBeforeBlocks());
+    }
+
+    /**
+     * @test
+     */
+    public function setSpaceBeforeBlocksProvidesFluentInterface(): void
+    {
+        self::assertSame($this->subject, $this->subject->setSpaceBeforeBlocks(' '));
+    }
+
+    /**
+     * @test
+     */
+    public function getSpaceAfterBlocksInitiallyReturnsEmptyString(): void
+    {
+        self::assertSame('', $this->subject->getSpaceAfterBlocks());
+    }
+
+    /**
+     * @test
+     */
+    public function setSpaceAfterBlocksSetsSpaceAfterBlocks(): void
+    {
+        $value = ' ';
+        $this->subject->setSpaceAfterBlocks($value);
+
+        self::assertSame($value, $this->subject->getSpaceAfterBlocks());
+    }
+
+    /**
+     * @test
+     */
+    public function setSpaceAfterBlocksProvidesFluentInterface(): void
+    {
+        self::assertSame($this->subject, $this->subject->setSpaceAfterBlocks(' '));
+    }
+
+    /**
+     * @test
+     */
+    public function getSpaceBetweenBlocksInitiallyReturnsNewline(): void
+    {
+        self::assertSame("\n", $this->subject->getSpaceBetweenBlocks());
+    }
+
+    /**
+     * @test
+     */
+    public function setSpaceBetweenBlocksSetsSpaceBetweenBlocks(): void
+    {
+        $value = ' ';
+        $this->subject->setSpaceBetweenBlocks($value);
+
+        self::assertSame($value, $this->subject->getSpaceBetweenBlocks());
+    }
+
+    /**
+     * @test
+     */
+    public function setSpaceBetweenBlocksProvidesFluentInterface(): void
+    {
+        self::assertSame($this->subject, $this->subject->setSpaceBetweenBlocks(' '));
+    }
+}